Ribbon fork actuating mechanism for typewriters and the like

ABSTRACT

An apparatus for typewriters and the like, particularly powerdriven apparatus for effecting a positive lifting and lowering of the ribbon fork thereof between a rest position and either one of two operating positions, in which a drive lever is operatively coupled to the ribbon fork actuating arm through a pair of intermediate levers, and control of the operating connection is effected by rigidly connecting the drive lever with one of the intermediate levers, whereby they act as one, or rigidly connecting the intermediate levers whereby they act as a single lever, the selection being determined by the positioning of a control member which correspondingly actuates the means for effecting such rigid connections.

United States Patent RIBBON FORK ACTUATING MECHANISM FOR TYPEWRITERS AND THE LIKE 5 Claims, 5 Drawing Figs.

11.8. CI. 197/157, 197/159 Int. Cl. B4 lj 33/56, B41 35/10 Field ofSearch l97/i57,

[56] References Cited UNITED STATES PATENTS l,800,854 4/l93l Barr 197/157 3,233,716 2/1966 Grashoff 197/157 Primary Examiner- Robert E. Pulfrey Assistant Examiner-Stephen C. Pellegrino Attorney-Hill, Sherman, Meroni, Gross and Simpson ABSTRACT: An apparatus for typewriters and the like, particularly power-driven apparatus for effecting a positive lifting and lowering of the ribbon fork thereof between a rest position and either one of two operating positions, in which a drive lever is operatively coupled to the ribbon fork actuating arm through a pair of intermediate levers, and control of the operating connection is effected by rigidly connecting the drive lever with one of the intermediate levers, whereby they act as one, or rigidly connecting the intermediate levers whereby they act as a single lever, the selection being determined by the positioning of a control member which correspondingly actuates the means for effecting such rigid connections.

PATENTED m2? 197:

SHEET 1 BF 2 Fig. 1

INVENTOR:

/. I, l V/ BY of M RIBBON FORK ACTUATIING MECHANISM FOR TYPEWRITERS AND THE LIKE BACKGROUND OF THE INVENTION The invention is directed to an apparatus for use in typewriters, particularly power-driven typewriters, and similar equipment for example, teletype machines, where high operating speeds are involved, for positively lifting and lowering the ribbon fork thereof between a rest position and one of two possible operating positions by means of an articulated lever system.

It frequently is advantageous to type in two colors on teletype machines, particularly for operations, in order to identify certain data on the recording carrier in a special manner. In teletype operations it is customary to differentiate the writing of two interconnected teletype machines by a different color identification. I

During the typing operations the ribbon fork must be lifted for each symbol to be printed, prior to the actual imprinting by the type bar, and subsequent thereto the ribbon fork must return into its rest position in order to enable a reading of the letter so printed. The high operating speeds to be attained require that the ribbon actuating movement be transmitted to the ribbon fork as positively as possible as at such high operating speeds it is no longer sufficient to merely accelerate the ribbon fork and let it impact without subsequent delayed action, for example against a suitable stop member. Conditions resulting from wear and impact breakdowns thereby occurring prevent a completely safe and dependable shifting from one color strip of ribbon to the other, whereby the desired identification of certain sections of typing by different color of ink cannot be assured. Consequently it is not merely advantageous but necessary to provide a positive drive of the rib bon fork at the high speeds involved.

Arrangements have already been proposed for lifting the ribbon in a positive manner, by means of the ribbon fork, into one of two operating positions. There has become known, for example, a ribbon actuating mechanism for power-driven typewriters and similar machines utilizing a lever system and a rocker arm coordinated to the type involved, whereby the bearing pin or rod for the support of the articulated lever system is pivotal around a stationary shaft for effecting the desired control by changing the positional height of the ribbon. There has also become known a ribbon lifting mechanism for office machines, particularly typewriters, whereby the stroke of the ribbon actuating means may be varied, in which two pivotal levers, preferably of U-shape, producing the ribbon stroke are interconnectable in various relative positions, assuming a stretched position as a type key is operated, with one of such levers independently following a predetermined angular path as each key is operated, independently of the length of the stroke to be effected.

While in such devices of the prior art positive transmission of force is achieved for lifting the ribbon fork into one to two operating positions, such arrangements have the disadvantage that the adjustment forces for changing the stroke length of the ribbon fork must be relatively large. More particularly, it is desirable in power-operated typewriters as well as teletypewriters to maintain the control forces for the individual functions as low as possible, first because the key pressure derived from the typing forces may be maintained at a low level, and secondly the received impulses need not be individually amplified electrically in order to provide adequate power for the desired functions.

The problem to which the invention is directed thus resides in the development of a device for the positive raising and lowering of the ribbon fork in which only low forces are required to effect the controlling operations, and yet provides a safe and completely dependable shifting of the ribbon fork.

SUMMARY OF THE INVENTION The present invention contemplates an apparatus which meets the requirements above set forth, in which a lever pivotal through a constant angular range by suitable drive means, is pivotally coupled over a linkage which includes intermediate levers pivotally connected to each other and to a moveable arm which actuates the ribbon fork, whereby a rigid connection can be selectively established, either between the drive lever pivotal by the drive means and the first intermediate lever of the intermediate levers or between the two intermediate levers of the chain.

In accordance with a preferred embodiment of the invention, the lever pivotally actuated by the drive means is rigidly connectable through the intermediate lever pivotally connected therewith to effect a positive locking of such intermediate lever on the pivotal axis of the drive lever. Such intermediate lever preferably is provided with an extension which is disposed at one side of the pivotal axis of the drive lever and cooperable with a blocking lever disposed at the opposite side of such axis which may be selectively pivoted by suitable control means into a position adjacent such pivotal axis, thereby locking the first intermediate lever to the drive lever.

In the preferredembodiment of the apparatus according to the invention the intermediate levers are connected by a pair of coupling links, the pivotal axis of which extend parallel to those of the intermediate levers. A stop member positioned on one of the intermediate levers cooperates with spring means biasing said coupling links, when in extended relation, in an overcenter position in which the two coupling links act as a single member to effect a rigid connection between the two intermediate levers, but if withdrawn from the overcenter position, the two coupling members may pivot without effect on the connection between the intermediate levers. The action of the coupling links is controlled by adjustment or control members which in one setting do not act upon the coupling links whereby they remain in extended position, and in another setting are operable to effect a pivoting between the coupling links and permit pivotal action between the two intermediate members.

The present invention thus enables the adjustment of the actuating mechanism for control of the ribbon fork stroke by utilization of very low adjustment forces, but at the same time results in a positive completely dependable stroke regardless of the length thereof, with the change being accomplished merely by change in the lever ratios in the articulated lever chain. Strokes of the ribbon fork of intermediate lengths are completely prevented in the present invention as the shift from one ribbon stroke to the other takes place in a single step without an intermediate range. Disturbances and breakdowns in the typing operations are thus to a very large extent excluded.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawing wherein like reference characters indicate like or corresponding parts;

FIG. I is a perspective view of a simplified presentation of the actuation mechanism for effecting the stroke of a ribbon fork;

FIGS. 2 and 3 are generally diagrammatic end elevational views of the mechanism of FIG. 1 illustrating changed positions during actuation of the mechanism to effect the smaller of the two possible stroke lengths transmitted to the ribbon fork in which FIG. 2 illustrates the ribbon fork in its lowermost or rest position; and

FIGS. 4 and 5 are views similar to FIGS. 2 and 3, respectively illustrating changed positions of the mechanism when adjusted for effecting the longer of the two possible adjustments of the strokes to be transmitted to the ribbon fork, in which FIG. 4 illustrates the ribbon fork in its lowermost or rest position.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1, a drive lever 1 in the form of a rocker arm rigidly supported on a drive shaft 2 and actuated by an eccentric, not shown, pivotally supports, on shaft 3', a lever 3 of platelike formation which has rigidly mounted thereon linkage-supporting rods 4 and 5 and a stop rod or pin 6, the levers l and 3 forming the first and second members of the transmission chain. The plate 3 is biased by means of a spring 7 in a counterclockwise direction to bring a stop member 8, formed on the plate, into engagement with the shaft 2, in which position the plate 3 may rotate through the same arcuate range as the drive lever l. Pivotally mounted on the rod 4, is a intermediate lever 9, which forms the third member of the chain, and a blocking lever 10, the levers 9 and 10 being freely pivotal on the rod 4 independently of one another. Rigidly carried by the lever 9 is a rod 11 which operatively couples the lever 9 to an arm 12, pivotally supported on a stationary shaft 13, with the ribbon fork 14 being pivotally connected to the lever arm 12.

Operatively connecting the two intermediate levers 3 and 9 are a pair of coupling links 15 and 16 which are pivotally connected by a rod 17, the opposite end of the link 15 being pivotally mounted on the rod 5 and that of the link 16 being pivotally mounted on the rod 18, rigidly connected with the intermediate lever 9. The coupling links 15 and 16 are urged in a direction to move the rod 17 to the right as viewed in FIGS. 2-5 by means of a spring 19, illustrated as being secured at one end to the link 15, with the link 15 engaging the stop rod 6 as clearly illustrated in FIG. 4. It will be noted that in this position the links l5, 16 are in an overcenter position with the axis of the rods 17 disposed at the right side of a line connecting the axes of the rods 5 and 18, whereby under compression forces the two links 15, 16 will act as a single rigid member, as such compression forces result in a supplementing of the force of the spring 19. The blocking lever 10 is urged in a clockwise direction by a tension spring 20, with the rod 18, in the positions illustrated in FIGS. 2 and 4, forming a stop which limits such movement of the blocking lever 10. The selective control of the switching over from one ribbon fork stroke to the other is accomplished by a control member 21 having an upwardly disposed extension 22 which may be selectively disposed adjacent the rod 17, as illustrated in FIG. 2, or pivoted downwardly out of engagement therewith, as illustrated in FIG. 4.

The functional connections existing to effect a transmission of the pivotal motion of the rocker drive arm 1 to the ribbon fork 14 whereby the shorter of the two operating strokes is to be effected, is illustrated in FIGS. 2 and 3. The rocker arm 1 is initially rotated by the eccentric, not shown, from driven position A to rest position B, and as the control member 21 has been pivoted into engagement with a stop 23, its extension 22 is disposed in the path of the rod 17, and as a result the coupling links 15 and 16 are pivoted out of their overcenter position (with respect to a line extending between the rods 5 and 18,) illustrated in FIG. 4 permitting the links 15 and 16 to freely pivot with respect to one another and the intermediate levers 3 and 9, whereby the links 15 and 16 have no effect on the movement of the respective intermediate levers 3 and 9. During the subsequent drive movement of the drive arm 1 and intermediate lever 3, as the intermediate lever 9 rotates in a clockwise direction about the rod 4 its initial movement will move the rod 18 carried thereby upwardly a sufficient distance to permit the spring to pivot the blocking lever 10 in a clockwise direction whereby the latter will engage the drive shaft 2 as illustrated in FIG. 3, thereby effecting a rigid connection of the intermediate lever 3 with the drive arm 1, the second intermediate lever 9, in effect, forming a coupling link between the drive arm I and the lever arm 12 whereby the ribbon fork 14 is positively coupled to the drive arm I and moved through a relatively short stroke. FIGS. 4 and 5 illustrate the functional connection utilized to transmit the pivotal motion of the drive rocket arm 1 to the ribbon fork 14, whereby the longer of the two operating strokes is effected.

If during the movement of the rocker arm 1 from A to B the control member 21 remains in a position as illustrated in FIG. 4 with its projection 22 disposed out of the path of the rod 17, the coupling links 15 and 16 will remain in extended overcenter positions with the spring 19 maintaining the link 15 in engagement with the stop pin 6. Consequently, the intermediate levers 3 and 9 are thereby rigidly locked together and function as a single member. At the same time, the rod 18 initially maintains the locking lever 10 out of blocking engagement with the drive shaft 2 until the lever 3 has pivoted suffrciently with respect to the rocker arm 1 to permit the nonlocking engagement of the arm 10 with the drive shaft 2 as illustrated in FIG. 5. During the drive movement of the rocket arm 1 from B to A the intermediate levers 3 and 9, in effect form a single connecting lever between the pivotal connection of the arm 9 with the arm 12 and that of the lever 3 with the rocket arm 1, thereby moving the fork actuating arm 12 through the longer of its two operating strokes.

It will be particularly noted that selection of the stroke is effected merely by the positioning of the control member 21 with respect to the rod 17, with the only force required to effect the selection being that required to move the control member 21 from one position to another, which obviously is very low.

Changes may be made within the scope and spirit of the appended claims which define what is believed to be new and desired to have protected by Letters Patent.

We claim:

1. In a mechanism for typewriters, particularly powerdriven typewriters and the like for effecting a positive lifting and lowering ofa ribbon fork thereof between a rest position and either one of two operating positions, the combination of a drive lever, rigidly mounted on a drive shaft, pivotal through a predetermined arcuate range, a pair of intermediate levers operatively connected to the drive lever for pivotal movement relative thereto, first means for selectively establishing a rigid connection between the two intermediate levers, and second means for establishing a rigid connection between the drive lever and one of said intermediate levers when said first means is inoperative, said intermediate levers operatively connecting the drive lever to said ribbon fork.

2. A mechanism according to claim I, wherein said second means is disposed to selectively establish a connection of said one intermediate lever with said drive shaft whereby movement of said one intermediate lever is limited to pivoting about the axis of said drive shaft.

3. A mechanism according to claim 2, wherein said second means includes an extension provided on said one intermediate lever engageable with said drive shaft at one side thereof, and a blocking lever, pivotal to selectively engage the drive shaft at the opposite side thereof.

4. A mechanism according to claim 1 wherein said first means includes a pair of pivotal coupling links which connect said intermediate levers and are spring biased in an overcenter position in engagement with a stop disposed on one of said intermediate levers, whereby said coupling links may act as a single rigid member connecting said intermediate levers in rigid relation, and a control member selectively engageable with said coupling links to enable movement of said coupling links out of said overcenter position for relative pivotal movement therebetween.

5. A mechanism according to claim 1, wherein said one intermediate lever is pivotally connected at one end thereof with the free end of said drive lever and at its opposite end to the other intermediate lever intermediate the ends thereof, said first means including a pair of coupling links having their adjacent ends pivotally connected, the free end of one of said coupling links being pivotally connected to one end of said other intermediate lever and the free end of the other of said coupling links being pivotally connected to said one intermediate lever intermediate the ends thereof, a stop member thereof, and a blocking lever pivotally connected to said one intermediate lever disposed for pivotal movement to selectively engage said drive shaft at the opposite side thereof to rigidly connect said one intermediate lever thereto, said blocking lever being engageable with means associated with said other intermediate lever when said coupling links are in overcenter position operative to dispose said blocking lever in a nonblocking position. 

1. In a mechanism for typewriters, particularly power-driven typewriters and the like for effecting a positive lifting and lowering of a ribbon fork thereof between a rest position and either one of two operating positions, the combination of a drive lever, rigidly mounted on a drive shaft, pivotal through a predetermined arcuate range, a pair of intermediate levers operatively connected to the drive lever for pivotal movement relative thereto, first means for selectively establishing a rigid connection between the two intermediate levers, and second means for establishing a rigid connection between the drive lever and one of said intermediate levers when said first means is inoperative, said intermediate levers operatively connecting the drive lever to said ribbon fork.
 2. A mechanism according to claim 1, wherein said second means is disposed to selectively establish a connection of said one intermediate lever with said drive shaft whereby movement of said one intermediate lever is limited to pivoting about the axis of said drive shaft.
 3. A mechanism accorDing to claim 2, wherein said second means includes an extension provided on said one intermediate lever engageable with said drive shaft at one side thereof, and a blocking lever, pivotal to selectively engage the drive shaft at the opposite side thereof.
 4. A mechanism according to claim 1 wherein said first means includes a pair of pivotal coupling links which connect said intermediate levers and are spring biased in an overcenter position in engagement with a stop disposed on one of said intermediate levers, whereby said coupling links may act as a single rigid member connecting said intermediate levers in rigid relation, and a control member selectively engageable with said coupling links to enable movement of said coupling links out of said overcenter position for relative pivotal movement therebetween.
 5. A mechanism according to claim 1, wherein said one intermediate lever is pivotally connected at one end thereof with the free end of said drive lever and at its opposite end to the other intermediate lever intermediate the ends thereof, said first means including a pair of coupling links having their adjacent ends pivotally connected, the free end of one of said coupling links being pivotally connected to one end of said other intermediate lever and the free end of the other of said coupling links being pivotally connected to said one intermediate lever intermediate the ends thereof, a stop member carried by said one of said intermediate members, spring means biasing said coupling links into engagement with said stop member with the coupling links in overcenter positions whereby they may act as a single rigid link connecting said intermediate levers in a rigid relation, a control member selectively engageable with said coupling links to enable movement of said coupling links out of said overcenter position, said second means including an extension provided on said one intermediate lever engageable with said drive shaft at one side thereof, and a blocking lever pivotally connected to said one intermediate lever disposed for pivotal movement to selectively engage said drive shaft at the opposite side thereof to rigidly connect said one intermediate lever thereto, said blocking lever being engageable with means associated with said other intermediate lever when said coupling links are in overcenter position operative to dispose said blocking lever in a nonblocking position. 